The Dual Tasks of Interviewers

Ting YanColm O‘Muircheartaigh

Jenny KellyPat Cagney

Rebecca JessoeNORC at University of Chicago

Kenneth RasinskiUniversity of Chicago

Gary EulerCenters for Disease Control and Prevention

What do interviewers do?

• Recruiting potential respondents– Introducing survey to potential respondents– Gaining cooperation – Screening for eligible respondents

• Administering interviews– Reading questions– Recording answers– Probing– Providing definitions

Desired qualities of interviewers

• When recruiting respondents– Adaptive and flexible (Converse & Schuman, 1974)

• Tailoring (Groves & McGonagle, 2001; Houtkoop-Steenstra & van den Bergh, 2002; Maynard & Schaeffer, 2002)

• Maintaining interaction (Groves & McGonagle, 2001)• Those who developed their own approach had lower refusal

and higher cooperation than those who follow a standard script

• When administering interviews– Technician like (Converse & Schuman, 1974)

• Standardized interviewing (Fowler and Magione, 1990)

• Conflicting?

How do interviewers affect survey error?

• Recruiting respondents– Nonresponse error

• If interviewer consistently attract respondents with a certain characteristic

• Administering interviews– Measurement error

• Interviewer bias • Interviewer variance

– If interviewers consistently influence responses in a certain way

Research questions

• Is there a relationship between interviewers’ performance at recruiting respondents and administering interviews? – Are interviewers who are good at recruiting

respondents also good at collecting data of good quality?

• How does interviewer experience mediate this relationship, if the relationship exists?

Data

• National Immunization Survey (NIS)– Nationwide, list-assisted random digit-dialing

(RDD) survey conducted by the NORC for the Centers for Disease Control and Prevention

– Monitors the vaccination rates of children between the ages of 19 and 35 months.

– 2007 Q3 data• 712 interviewers worked • 499,490 telephone numbers dialed

– 4,438 interviews obtained

Which interviewers were includedin the analysis?

• Interviewers who had completed interview(s) on first contact– 295 interviewers

• 3114 completes

Measures of recruitment task

• (First contact) Refusal rate =# refusals/# first contact cases

• (First contact) Completion rate=# completes/# first contact cases

• (First contact) Eligibility rate=# eligibles/# first contact cases

• Denominator: first contact cases– Virgin (fresh) cases or cases that were dialed by

autodialers only. – They haven’t been touched by humans before sent to the

current interviewer.

• Refusal conversion rate=# converted refusals/# refusals

Measures of administration task

• Interviewer effect (ρint)

• Adherence to standardized interviewing (monitoring data)

• Item nonresponse

• Interview time (cost)

Good openers vs. Bad openers

• Good openers: 3 out of 4 rates are above medians

  Good Openers

Bad Openers

# of interviewers 100 195

Average # of interviews 13 9

Refusal Rate 10.46% 13.09%

Refusal Conversion Rate 1.34% 0.32%

Completion Rate 0.30% 0.15%

Eligibility Rate 3.91% 2.37%

Good openers vs. Bad Openers (II)

• When experience is introduced– Median split on # of days worked at NORC

 Number of

InterviewersAverage Number of

Interviews Completed

 Good

OpenersBad

OpenersGood

OpenersBad

Openers

Experienced 67 83 15 11

Inexperienced 33 112 11 8

Good openers vs. Bad Openers (III)

• When experience is introduced– Median split on # of days worked at NORC

 Refusal

Rate

Refusal Conversion

RateCompletion

RateEligibility

Rate

  Good Bad Good Bad Good Bad Good Bad

Experienced 10.5% 12.5% 1.7% 0.6% 0.32% 0.16% 4.1% 2.2%Inexperienced 10.5% 13.5% 0.5% 0.1% 0.27% 0.15% 3.6% 2.5%

ρint

• ρint : Intra-interviewer correlation• Deffint=1+ ρint*(m-1)• Hierarchical linear models

– Respondent data as level 1 data– Interviewer data as level 2 data– Unconditional model with no explanatory

variables at either level– ρint=between-interviewer variance/total

variance

ρint (II)

Family Income

Good openers Bad openers

Experienced 0.0825 0.0337

Inexperienced 0.2395 0.1053

0.1236 0.0786

ρint (III)

# of people living in household

Good openers Bad openers

Experienced 0.0082 0.0408

Inexperienced 0.0004 0.0139

0.0013 0.0239

ρint (IV)

# of Vaccines Received (Average)

Good openers Bad openers

Experienced 0.0003 0.0003

Inexperienced 0.0041 0.0026

0.0234 0.0085

Monitoring scores

• Monitoring items– Read questionnaire verbatim– Probe without biasing or leading/Probing for Don’t

Knows– Reads scales as directed etc.

• Scores– 1=Error– 2=No Error– 3=Outstanding

• Item-level monitor score for each interviewer• Overall summary score for each interviewer

Monitoring scores (II)

• Good openers on average have higher mean scores than bad openers, but difference sig. only for one monitoring item– Read Questionnaire Verbatim– Verifies dates and confirms spelling– Properly obtains all provider information– Use job aids as needed– Reads scales as directed– Records open-end response verbatim– Probes without biasing or leading/Probes Don’t

Knows

Summary scores across monitoring items

6.80

7.00

7.20

7.40

7.60

7.80

8.00

8.20

8.40

8.60

Good Opener Bad Opener

Experienced

Inexperienced

Item Nonresponse• A set of 24 questions every one had to answer• Item nonresponse rate=# of times R didn’t

provide an answer /24

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

G ood Opener B ad Opener

E xperienc edInexperienc ed

Average Interview Duration (cost)

• Time spent on completing an interview– The longer the interview time, the more costly

27

28

29

30

31

32

33

34

G ood Opener B ad Opener

E xperienc edInexperienc ed

Provider consent rate

66%

68%

70%

72%

74%

76%

78%

80%

82%

Good Opener Bad Opener

Experienced

Inexperienced

(79.8%) (74.9%)

Conclusions and Discussion

• Good-opener interviewers • More completes• Higher refusal conversion, completion, and eligibility rates• Lower refusal rate

• Good-opener interviewers• Higher intra-interviewer correlation• But more adherence to standardized interviews (higher

monitoring scores)• More missing data

• Are good openers also good at collecting data of good quality?

• No one clear answer• Depends on which measures of interviewing tasks

• Experience didn’t matter much

Limitations and Next Steps

• Only used various rates to measure interviewers’ performance at the recruitment stage

• Demographic compositions by interviewer status• Nonresponse error by interviewer status

• Only used proxy measures of data quality• Direct measures of measurement bias

• Interviewer characteristics and respondent characteristics not considered

• Bringing in interviewer and respondents characteristics into the picture

• Examining the effect of matched interviewer and respondents characteristics

Thank You!

Yan-ting@norc.org